All articles starting with O

Overseas Service Ribbon

Overseas Service Ribbon (OSR), U.S. military ribbon for completed overseas tours; Army version established April 10, 1981; Navy/Marine Corps version requires 12 months overseas or 30/45 days after August 14, 1974.

Overseas Vietnamese

Overseas Vietnamese are people of Vietnamese birth or ancestry living outside Vietnam, a diaspora of about 3.4 million that grew after the 1975 fall of Saigon.

Sep 19, 2026

Overseer of cattle

The Overseer of cattle (imy-r ih.w) was an ancient Egyptian official title for the head of the state's cattle administration, attested from 2345 to 1150 BCE.

Sep 19, 2026

Overseer of royal works

The overseer of royal works, Egyptian imy-r k3t nbt nt nswt, was a senior Old Kingdom office organizing labor and resources for royal projects, above all pyramids.

Sep 19, 2026

Overseer of the treasuries

The overseer of the treasuries was an ancient Egyptian official in charge of the state treasury, attested from the First Dynasty into the New Kingdom.

Overshoot (signal)

Overshoot in signal processing is the excursion of a reconstructed or filtered signal above its true value near a transition, paired with an undershoot below it.

Overshooting top

An overshooting top is the dome-like protrusion of a thunderstorm's cloud top above the anvil, driven by a very strong updraft and used as a satellite indicator of storm intensity.

Overstrength

Overstrength is the ratio of a structure's actual lateral strength to the strength required by seismic design provisions, central to earthquake engineering because codes rely on reserve strength to prevent collapse.

Overthinking (reasoning models)

Overthinking in reasoning models is the tendency of large language models trained to reason at length to generate unnecessary tokens that waste compute, increase latency and cost, and sometimes lower accuracy on simple tasks.

Overthrow and death of Khosrow II

The overthrow and death of Khosrow II (سرنگونی و قتل خسرو پرویز) was a court coup at Ctesiphon in February 628 that deposed and executed the Sasanian king.

Overthrow and killing of False Dmitry I (1606)

The overthrow and killing of False Dmitry I was the Moscow rising of 17 May 1606, in which conspirators led by Vasily Shuisky killed the pretender tsar.

Overthrow of Biron and regency crisis (1740)

The overthrow of Biron (Свержение Бирона) was a palace coup in Saint Petersburg in November 1740, in which Field Marshal Münnich arrested the regent of Russia.

Overthrow of Dhana Nanda by Chandragupta Maurya

The overthrow of Dhana Nanda by Chandragupta Maurya (धनानंद का पतन) was Chandragupta's capture of the Nanda capital Pataliputra around 321 BCE, aided by Kautilya.

Overthrow of Slobodan Milošević

The 5 October 2000 overthrow, or Bulldozer Revolution, ended Slobodan Milošević's 13-year rule after he refused to concede the 24 September election to Vojislav Koštunica, prompting mass Belgrade protests, a miners' strike, and security-force non-intervention.

Overthrow of Sophia, 1689

The overthrow of Sophia (Падение Софьи 1689 года) was the removal of regent Sophia Alekseyevna by her half-brother Peter I in 1689, leaving Peter effective ruler of Russia.

Overthrow of Taksin

The overthrow of Taksin was the deposition and execution of King Taksin of Thonburi in 1782, after a rebellion led by Phraya San seized the capital.

Overthrow of the Aghlabids and proclamation of the Fatimid Imamate

The overthrow of the Aghlabids (قيام الدولة الفاطمية) in 909 ended Aghlabid rule in Ifriqiya and installed Ubayd Allah al-Mahdi as the first Fatimid imam-caliph.

Overthrow of the Hawaiian Kingdom

Overthrow of the Hawaiian Kingdom: the January 17, 1893 deposition of Queen Liliʻuokalani by the Committee of Safety led by Sanford Dole, aided by U.S. Minister Stevens and Marines from the USS Boston, leading to the Republic of Hawaii and 1898 annexation.

Overthrow of the Lü clan

The Overthrow of the Lü clan (诛吕安刘) was a pair of palace coups in 180 BC that destroyed Empress Lü's family and enthroned Emperor Wen.

Overthrow of the Nandas by Chandragupta Maurya

The overthrow of the Nandas by Chandragupta Maurya (चंद्रगुप्त मौर्य द्वारा नंद वंश का पतन) replaced the Nanda dynasty of Magadha with the Mauryan dynasty, about 325 to 321 BC.

Overthrow of the Regency of Sophia

The Overthrow of the Regency of Sophia (Свержение царевны Софьи) was the bloodless palace struggle of 1689 in which seventeen-year-old Peter I ended his half-sister Sophia's regency.

Overthrow of the Roman monarchy

The overthrow of the Roman monarchy, also known as the expulsion of Tarquin, was the removal of the last king, Lucius Tarquinius Superbus, traditionally dated to 509 BCE.

Overtime (ice hockey)

Overtime (ice hockey): extra sudden-death periods deciding tied games. NHL uses 5-minute 3-on-3 plus shootout in the regular season and unlimited 20-minute 5-on-5 periods in the playoffs; IIHF and NCAA use variants.

Overtime (sports)

Overtime (sports): extra playing time added when a match is tied after regulation, including sudden death, fixed extra periods, and shootouts; NBA five-minute periods, NFL 10-minute possession-guaranteed overtime, IIHF 3-on-3 sudden death, IFAB extra time.

Overtime Elite

Overtime Elite (OTE): Atlanta-based professional basketball league and academy for elite players aged roughly 15-20, launched 2021 by Overtime; originally $100,000 minimum salaries, now a scholarship model; alumni include the Thompson twins, Alex Sarr, and Rob Dillingham.

Overton window

The Overton window, or Window of Political Possibilities, is a policy-change model developed in the mid-1990s by Joseph P. Overton of Michigan's Mackinac Center, describing the range of policies politicians can back without electoral risk; it shifts, expands, or contracts with public opinion.

Overtone

An overtone, also known as an upper partial or superharmonic, is any frequency component of a complex sound above its fundamental; overtones largely determine timbre, or tone color.

Overtone singing

Overtone singing, also called harmonic or throat singing, is a vocal technique in which one singer sustains a drone while amplifying a single harmonic into a separate melody. Centered in Tuva, Mongolia, and the Altai region, it was inscribed by UNESCO for Mongolian Khoomei in 2009.

Overtopping

Overtopping, or wave overtopping, is the passage of water from wave run-up over the crest of a seawall, dike, or breakwater, which can flood the hinterland and endanger people.